2011 marks Guido Fonseca's first year with the Windy City ThunderBolts. He signed with the team on August 1, 2011. The ThunderBolts are Fonseca's third Frontier League team after the Kalamazoo Kings and Rockford RiverHawks. He began his professional career in the Cleveland Indians organization after they selected him in the 12th round of the 2008 amateur entry draft out of the University of Northern Iowa. The highest level he reached was low-A Mahoning Valley. As a senior at Northern Iowa in 2008, he went 9-2 with a 4.50 ERA in 14 starts. Guido attended South Hills High School in Covina, California.